Not Applicable
This application related to miniaturized power supplies and battery chargers. In particular this application discloses an inventive transformer and inventive control element which permit the manufacture of smaller and lower cost AC/DC power supplies and battery chargers.
The use of planar transformers is well known in the art. See for example the following patents:
U.S. Pat. No. 5,502,430
U.S. Pat. No. 5,754,088;
U.S. Pat. No. 5,949,321;
U.S. Pat. No. 6,069,548;
U.S. Pat. No. 6,144,276;
U.S. Pat. No. 6,208,531.
Patents related to miniature transformers and miniature power supplies and battery chargers are also known in the art. See for example the following patents:
U.S. Pat. No. 5,534,839, and
U.S. Pat. No. 6,100,664.
U.S. Pat. No. 6,208,531 is related to a power converter having magnetically coupled control.
None of the prior art provides a power supply/battery charger which has a universal input which accepts a DC input of between 10-30 VDC or an AC input of between 85 VAC to 265 VAC and between 50-60 Hz and provides a regulated DC output voltage or current; which utilizes a planar transformer; which provides a programmable control which allows the device to work with any battery chemistry, as well as a variable power source such as a solar cell; which eliminates the need for bulky hold up capacitors; which matches the impedance of the power source and the impedance of the load, and which can be electrically isolated using magnetic isolation.
For the purpose of this disclosure, all U.S. patents and patent applications and all other publications referenced herein are incorporated herein by reference in their entirety.
Applicant has invented a miniature power supply and battery charger with a universal input, so that it functions as a universal power module. The inventive device is connected to a power source, which can be AC or DC, which is connected to a transformer, which consists of a primary coil, a secondary coil and a magnetic core, the secondary coil being configured to provide a regulated DC output voltage and/or current. A control circuit is electrically connected to the power source for controlling first and second FET""s electrically connected to the control circuit, the first FET being electrically connected to an upper portion of the primary coil such that when the first FET is activated only the upper portion of the primary coil is utilized in the transformer, the second FET being electrically connected to a lower portion of the primary coil such that when the second FET is activated the entire primary coil is utilized in the transformer. The control circuit is configured to detect the input voltage of the power source and above a predetermined threshold voltage activate the second FET so that the power module operates as a high voltage input converter and below the predetermined threshold voltage activate the first FET so that the power module operates as a low voltage input converter.
The inventive universal power module utilizes an inventive planar transformer design which contributes to its miniature size. The inventive planar transformer includes a triple insulated primary winding formed into a planar coil, and a secondary winding formed on a printed circuit board (PCB). The triple insulated primary winding and secondary winding are sandwiched between upper and lower magnetic core material, the triple insulated primary winding and secondary windings being in physical contact with each other. The use of the triple insulated primary winding provides safety isolation.
The control element includes a battery module circuit consisting of a primary control circuit and a DC/DC converter for monitoring and maintaining the charge on a secondary battery. The primary control circuit regulates the input power and is connected to a DC/DC converter which produces a regulated DC current used to charge the battery. The primary control circuit has three input lines for programming the primary control circuit, and the DC/DC converter having three input lines for programming the DC/DC converter. As few as a single wire could be used for programming, however three lines are standard using the JTAG standard.
The control circuit can also include a switch mode power supply which is configured with an inventive circuit to track the voltage of a rectified cycle of the AC input source. This permits the elimination of bulky hold up capacitors, thereby aiding in the miniaturization of the device.
The control circuit can also include an inventive source impedance matching circuit which includes a charger electrically connected to a power source and a battery, and a control circuit which ramps up the current from the power source until the load impedance of the charger is matched to the impedance of the power source.
The control circuit can also be programmably constructed and arranged so that the DC output voltage and/or current of the universal power module may be programmably set by the user. This allows the device to be utilized with different types of batteries, on the fly.
Further miniaturization is permitted by using a high current low loss diode connected to the secondary coil of the transformer. The high current low loss diode includes first and second high current, low on-resistance power MOSFETS electrically connected between an input and an output. A control circuit electrically connected to the first and second MOSFETS which turns off the first and second MOSFETS when the voltage on the output is higher than the voltage on the input and which turns on the first and second MOSFETS when the voltage on the input is higher than the voltage on the output.
The transformer utilized in the inventive device uses an inventive construction to further reduce the size. The transformer uses a bobbin having opposite sides. PCB support pins extend from each of the opposite sides of the bobbin, first and second windings are located on each of the opposite sides of the bobbin, and a core is attached to the bobbin. Two PCB""s are attached to the PCB support pins, one PCB on each side of the bobbin. The windings may be located either around the support pins or on the PCB""s themselves.
The inventive universal power module can also be electrically isolated, with the primary coil of the transformer being housed in a paddle and the secondary coil being housed in a mating receptacle. In this manner a load device is electrically connected to the secondary coil and electrically isolated from the power source.